https://hardy0700.wordpress.com/2016/07/16/raspi-3-huawei-3531-sms-server/?fbclid=IwAR1mNVn2R2gddIEJ-tm9N5f-7TwJe0huJkiedqqGkNrDP08ALdBG5GiMvHE

http://newsimoffer.com/grameenphone-gp-internet-modem-price-configuration/

https://wammu.eu/

https://docs.gammu.org/gammu/